Function transform 

pub fn transform(
    server: &str,
    tool: &str,
    text: &str,
    budget_tokens: usize,
) -> Option<String>

If text is a Repomix pack result, archive it verbatim and return a compact summary + a ctx_expand retrieval handle. Returns None for non-pack tools, non-JSON output, or when archiving is unavailable (caller falls back).